Action does not work with `pull_request` events

[skearnes]

The pull_request workflow event uses a different value for GITHUB_REF that does not include the branch name (in contrast to the push event); instead, it includes information about the PR, e.g. refs/pull/72/merge. This causes git push to fail with errors like this:

! [remote rejected] HEAD -> refs/pull/72/merge (deny updating a hidden ref)

[trsvchn]

I was able to reproduce an issue.
And figured out that in addition to GITHUB_REF there are some addition env vars: GITHUB_HEAD_REF, GITHUB_BASE_REF. And they have diff values on pushes and PRs:

on push:

DEBUG: GITHUB_HEAD_REF: 
DEBUG: GITHUB_BASE_REF: 
DEBUG: GITHUB_REF: refs/heads/pr-test2
DEBUG: INPUT_TARGET_BRANCH: 
DEBUG: BRANCH: pr-test2

on PR:

DEBUG: GITHUB_HEAD_REF: pr-test2
DEBUG: GITHUB_BASE_REF: master
DEBUG: GITHUB_REF: refs/pull/2/merge
DEBUG: INPUT_TARGET_BRANCH: 
DEBUG: BRANCH: merge

As you can see it causes some problems with branch name and later with pushing step.
I think now we can use this info to fix this issue

[trsvchn]

It seems to work now: trsvchn/colab-badge-action-test/pull/9
I am new to github actions so, I used these resources to solve a problem.

• Fix a Git detached head?
• HTTP-based Git access by an installation
• Push to origin from GitHub action
• Making pull requests to a GitHub repository automatically with GitHub Actions
• GitHub Actions: How to Automate Code Formatting in Pull Requests

[skearnes]

Thanks for digging into that!

[trsvchn]

Thanks for digging into that!

Quarantine gives me too much free time at home)